In general, the various lumens of an endoscope that has been used on a patient are first cleaned with brushes that remove gross debris, like fecal matter, and are then flushed with a liquid such as alcohol or water, and dried with pressurized air forced through the lumens. The outside surfaces of the endoscope are then wiped dry with a lint-free cloth.
Occasionally, an instrument may not be thoroughly dried or the drying step may be skipped accidentally altogether. Thus, moisture on the internal or external surfaces of the instrument may be inadvertently introduced into the sterilization system. Water splashed accidentally into the chamber may also increase the level of moisture present when sterilization begins.
It is generally desired to limit the amount of moisture present in a vapor phase sterilization system. Water in the sterilization chamber, or on the internal or external surfaces of a load placed in the chamber, may act as a barrier and prevent sterilant vapor from effectively contacting the surfaces to be sterilized. Also, water may cause condensation of the liquid sterilant, thereby diluting the concentration of sterilant vapor and reducing its efficacy or requiring longer kill times. In addition, condensed sterilant, such as liquid hydrogen peroxide, may degrade or harm the contents of the sterilization chamber. Synthetic materials employed in flexible endoscopes, for example, may be degraded by condensed hydrogen peroxide.
When a sterilant vapor such as hydrogen peroxide, which is a strong oxidizer and corrosive to a wide range of metals, is employed, a conventional humidity detector, which directly senses humidity levels, should not be employed. The corrosive vapors may easily damage or destroy such a humidity detector.
There is a need for a method of accurately detecting moisture levels in a vapor phase sterilization system, to alert the user to remove any excess water (i.e.. an amount of water that is unacceptable for the intended application) before sterilization proceeds. There is a further need for an indirect method of detecting moisture in a sterilization system employing a corrosive vapor sterilant.